CN101506615B - Method of contact-less measurement of two-layered three-dimensional objects by single-view optical ombroscopy - Google Patents

Abstract

A method for the contact-less measurement of two-layered three-dimensional objects by single-view optical ombroscopy. According to the invention, in order to measure without contact a three-dimensional hollow object (32) that is translucent or transparent to visible light, an image of the object is acquired by single-view optical ombroscopy along a viewing axis (34) while examining said object under visible light and said image comprising at least one luminous line, an equation is established for relating at least one opto-geometrical parameter of the object with at least one geometrical parameter of the luminous line, the geometrical parameter is determined, and the opto-geometrical parameter is determined using the equation and the geometrical parameter thus determined.

Description

Be used for having the method for two-layer three-dimensional body by single-view backlit shadowgraphy method contactless measurement

Technical field

The present invention relates to a kind of single-view backlit shadowgraphy method (ombroscopieoptique à une seule vue, the English single-view backlit shadowgraphy of being) of passing through and be used for contactless type (contactless) measurement or characterize to have the method for two-layer three-dimensional body.

This method is particularly useful for:

-contactless measurement has the distortion or the roughness of the inside surface of two-layer clear hollow object,

-measurement has the refractive index of two-layer isotropy clear hollow object,

-measurement has the thickness of the internal layer of two-layer clear hollow object,

-restore the internal layer unanimity (mise enconformit é) that makes such object by control,

-calculate the roughness of such object based on three-dimensional representation (reconstruction, reconstruct, reproduce) by the spherical harmonic analytical approach.

There are a lot of difficulties in contactless type space measurement with respect to two-layer three-dimensional hollow visible transparent or translucent at least.

In order to overcome these difficulties, known use is by the measuring technique of back illumination backlight photographic process.This technology is applied to the object can single-view observed, and particularly those are difficult to enter the sign of the object of (acc é der).

In the present invention, the object that is characterized mainly is a hollow sphere.

The invention enables can be from the backlight photographic negative (clich é ombroscopique) of this object, spatially estimate the area of the inside surface of observed object, and take a picture and the state of the inside surface of determining to have two-layer translucent hollow object is observed in interferometry by means of backlight.

Background technology

Known two kinds of technology are used to measure the thickness and the diameter of hollow sphere, i.e. interferometry and roentgenography.If object be placed on a complexity base layer structure (foundation structure, infrastructure) in and can not operate from the outside, can not use roentgenography so.

Certainly, the method that exists some to use single image that object is carried out three-dimensional representation (or reproduction), but their application (enforcement) supposes that these objects have a large amount of symmetries.In addition, representation is on the whole.

Interferometry is a kind of accurate method that can be used in the complicated base layer structure, but its enforcement is very hard to tackle.

By following we with the document of reference, also knownly be used to measure two kinds of methods of three-dimensional body by back illumination backlight photographic process,

The International Application No. WO of announcing on September 30th, 2,004 2004/083772, " Method of measuring three-dimensional objects by single-viewoptical shadowgraphy "

The International Application No. WO of announcing on March 23rd, 2,006 2006/030149, " Method of measuring dimensional objects by single-view opticalshadowgraphy, using light propagation optical laws ".

Disclosed Technology Need is systematically set up the tables of data that comes from the simulation of being undertaken by optics software in the document [1], and this table has been contained the four corner of the different size of observed object.Data in this table can date back to the dimensional measurement of object by interpolation method.The range of size of including in the tables of data is big more, if wish to keep a certain degree of accuracy, the time of then setting up this table is long more.

The disclosed technology of document [2] is based on Si Nieer-how much (geometrical optics) principles of Descartes's optics (Snell-Descartes optogeometric laws), and only constitutes the guestimate of the inside surface state of the hollow object that hope is characterized.In this technology, directly use the inwall of observed curved surface as the internal layer of this object.In addition, viewing area is restricted to the equatorial plane (plan é quatorial) of spherical generally object.Use this technology can't carry out the space representation of the inside surface of hollow object.In addition, in document [2], do not mention space representation method.

Summary of the invention

The objective of the invention is to address the aforementioned drawbacks.

It relates generally to the backlighting photography phase images based on object, the three-dimensional representation of the inwall of two-layer object on the zone in the equator of close this object.

Except this contactless type optical means, the another kind of method that characterizes a plurality of positions (points) is used.Carry out three-dimensional representation generally thus to the inwall of the translucent or transparent two-layer object of light.

Because whole inwall is by representation, therefore this three-dimensional representation is generally.For this reason, use the specific function of determining the deformed sphere parameter.

The feasible zone that can observe near the object equator of backlight photographic process.Make the image of observing in this way necessary analyzed.Information is present in the included key light ring of image, and this key light ring is a viewing plane and the intersecting (intersection runs through) of caustic surface.

In the distortion of key light ring with appear at interference on the inwall of two-layer object (there is linear relationship in disturbance between disturbance).This relation is set up a kind of from the two-dimensional signal of image acquisition and the correspondence between the three-dimensional information.

From the space representation of two-dimensional signal is most important element of the present invention (key element).Until now, nobody attempts to set up the contact between the interference of inwall of the caustic surface of distortion and hollow object.

In the present invention, interferometry is used for the thickness of direct Measuring Object internal layer and the therefore distortion of (measurement) this internal layer.Yet this method makes only observes in one of two-layer object limited zone, because two-layer object is placed on one to a great extent in the complex environment of constrained motion usually.

Here it is why the space representation of the inside surface of two-layer object be based on the combination (merging) of backlight photographic data and interferometry data.Therefore the combination of these data is, after space representation based on the image that obtains by back illumination backlight photographic process, and another important element of the present invention.

Particularly, the present invention relates to a kind of method that is used for the contactless measurement three-dimensional hollow, this three-dimensional hollow has inwall thus, and this object comprises skin and internal layer, this object is translucent or transparent with respect to visible light, the method is characterized in that:

-by the single-view backlit shadowgraphy method, by observing the image that object obtains this object with visible light, this image comprises at least one isolychn (light line, luminous line) (ring of light or light belt) along the first observation axle,

-set up the equation (equation, equation) that at least one geometric parameter with at least one the optics geometric parameter of object and isolychn interrelates,

-determine this geometric parameter, and

-determine this optics geometric parameter by equation and definite thus geometric parameter.

According to a preferred implementation as the method for the object of the invention:

-based on the image and the equation of object, carry out the three-dimensional representation of inwall on the close zone in this object equator of three-dimensional body, this representation provides first group of data,

-determine the thickness of object internal layer,

-determine the second group data relevant according to the thickness of determining thus with the distortion of this internal layer, and

-carry out the representation of the whole inwall of object by first group and second group of data.

Preferably, be based upon the distortion of isolychn and appear at linear relationship between the interference on the inwall of object, so that determine second group of data.

According to first embodiment, determine the thickness of the internal layer of three-dimensional body by interfere measurement technique as the method for the object of the invention.

According to second embodiment, determine the thickness of three-dimensional body internal layer by the backlight photographic measurement of carrying out along the second parallel observation axle with the first observation axle.

According to the 3rd embodiment, by observing the thickness that the internal layer of three-dimensional body is determined in a backlight photographic measurement of carrying out after the rotation of carrying out object along first.

Preferably, the representation of the whole inwall of three-dimensional body is by realizing in conjunction with first group of data and second group of data by means of least square method.

According to a embodiment, determine respectively by the refractive index of the internal layer of three-dimensional body and two optics geometric parameters that outer field refractive index constitutes according to two geometric parameters that constitute by interior layer thickness and outer layer thickness respectively as the method for the object of the invention.

Description of drawings

With reference to accompanying drawing, only be the description of indicative ground and complete nonrestrictive illustrative embodiments by what provide below reading, will understand the present invention better, in the accompanying drawings:

Fig. 1 is can back illumination backlight photograph schematic representation of apparatus used in this invention,

Fig. 2 is the radial profile (profil radial) of the back illumination backlighting photography phase images that obtains in implementing the process of the method according to this invention,

Fig. 3 is the image by the inside surface of the hollow object of the method according to this invention representation,

Fig. 4 shows this surperficial xsect,

Fig. 5 is can another back illumination backlight photograph schematic representation of apparatus used in this invention,

Fig. 6 be can interferometric measuring means used in this invention synoptic diagram, and

Fig. 7 and Fig. 8 have schematically shown and have been used for characterizing respectively hollow circular cylinder and the ellipsoidal back illumination backlight of hollow photographic means according to the present invention.

Embodiment

The invention is characterized in

(a) in three-dimensional representation near the little contiguous place in the equator of the transparent substance that wish to characterize, and

(b) combination of data (merging).

These data obtain by visible light single-view backlit shadowgraphy device and interferometric measuring means.

Combine with the optics light propagation model by the observation of visible light backlight irradiation to transparent substance, this optics light propagation model is considered the interaction of this propagation on the different interfaces of object.This measuring principle makes and the direct measurement to the image that obtains by the backlight photographic process can be interrelated with the distortion of the inside surface of the object of studying and the size quantity of this object.

Back illumination backlight photographic process is a kind of simple measuring method that is used to study flat object, but for three-dimensional body, the image that is obtained by this method does not provide enough information.This is because the viewed image of object xsect not merely is the image of the xsect of the object lens by the backlight photographic means: it is the image by the xsect of these lens and object itself.

Make and the size characteristic of directly measuring with object can be interrelated by the observation of interferometry object.

Estimate by means of the backlight photographic process being measured the space that combines the inside surface that has provided observed object with the interferometry measurement based on the algorithm of least square method.

Complementarity between back illumination backlight photographic process and interferometry is simpler, to be applied in the labyrinth, wherein have only one to observe axle (axe de vue), these are different with the x-ray tomography photography, the x-ray tomography photography is generally used for this situation (three-dimensional) but must observes object at several incident angles, and can not observe object at several incident angles in this case.

Two-layer hollow sphere (spherical object) is studied, known may be except the optical index of internal layer all features, the especially optical index of this two-layer hollow sphere and every layer thickness.

Backlight photograph Faxian illustrates the ring of light (Luminous Ring, luminous ring).Each ring of light is characterised in that the convergence of light, is called " caustic surface ".Contact between the inside surface of the ring of light of observed correspondence and object has been set up in the analysis of this caustic surface.This feasible direct measurement that can utilize image.

According to measuring method of the present invention mainly based on this analysis and based on the combination of the measurement (result) by least square method.

Below provided for a hollow sphere object, be called " hollow sphere " more simply, implemented an example as the method for the object of the invention, this hollow sphere comprises two-layer and is transparent to visible light.

In this example, ground floor is the hollow polymer spheroid, and its external diameter (outer dia) and thickness equal 2430 μ m and 175 μ m respectively, and its optical index equals 1.54 at the predominant wavelength place of visible light source; And the second layer has the thickness of 100 μ m and in the optical index at this wavelength place 1.16.

Fig. 1 is the back illumination backlight photograph schematic representation of apparatus that can be used in this example, comprises a collimation visible light source 2, object lens 4 and screen (é cran) 6.The object of studying 8 is placed between light source 2 and the object lens 4; Its skin has mark 12 and its internal layer has mark 10.Also can see from light source by object and then scioptics light 14 to screen.

Let us is at first considered all features of key light ring, and the key light ring is most of ring of light visible, that obtained by the single-view backlit shadowgraphy method on real image just.

Based on such image (visible key light ring on this image), can form the radial profile of this image, this ring of light is labeled with intensity peak on this radial profile.

Such section is shown among Fig. 2.At X-axis input pixel quantity (pxl), and at Y-axis input amplitude (gray-scale value, gray level) (I).The key light ring is with peak P mark, and arrow B is represented the outward flange of object.The center of object is corresponding to Y-axis (axis of ordinates).

The ring of light is owing to the convergence of the light of the reflection of following same type and transmission light path.In this case, the path of following corresponding to the light among Fig. 1 14 as the light path of this ring of light cause.

The convergence of light is also referred to as " caustic " and constitutes three-dimensional outer (enveloppe) of these light.These key light rings are these caustic surfaces and the intersecting of the sensor that in fact is arranged on the observing system of the position of screen 6 among Fig. 1.

The sensor that should be noted that observing system can carry out little moving along observing axle around its initial position.Little mobile being represented as of the type uObserving axle is the optical axis 16 of lens 4 among Fig. 1.

In ideal situation, the inside surface 18 (Fig. 1) of observed object is perfect spheroid, and the observed ring of light (anneau lumineux) then is a circle (cercle).

Consider to use $\mathrm{\ρ}\→R_u^{*}\left(\mathrm{\ρ}\right)$ In from light source 2 and from the light of optical axis 16 apart from the ρ position, by after the whole optical system that is formed by object 8 and lens 4, it will be apart from interrelating with intersect (intersection) of this light with the sensor of observing system at this light.So can write out following formula:

$R_u^{*}\left(\mathrm{\ρ}\right)=h_1\left(\mathrm{\ρ}\right)+{\mathrm{uh}}_2\left(\mathrm{\ρ}\right)$

H wherein ₁(ρ) and h ₂(ρ) be smooth applying (level and smooth use, applications lisses), that is to say on R it is indeterminate difference, they only depend on optical system.They are provided by following formula:

$h_1\left(\mathrm{\&rho;}\right)=\frac{\mathrm{\&rho;}}{\mathrm{<figure-callout\; id="2"\; label="cos"\; filenames="H2007800303411E00011.png"\; state="\{\{state\}\}">cos</figure-callout>}2\mathrm{\&psi;}}$

$h_2\left(\mathrm{\&rho;}\right)=\frac{1}{f}{h}_1\left(\mathrm{\&rho;}\right)+\tan 2\mathrm{\&psi;}$

And

$\mathrm{\&psi;}=\arcsin \left(\frac{\mathrm{\&rho;}}{r_1}\right)-\arcsin \left(\frac{n_{\mathrm{ext}}\mathrm{\&rho;}}{n_{S_1}{r}_1}\right)+\arcsin \left(\frac{n_{\mathrm{ext}}\mathrm{\&rho;}}{n_{S_1}{r}_2}\right)-\arcsin \left(\frac{n_{\mathrm{ext}}\mathrm{\&rho;}}{n_{S_2}{r}_2}\right)+\arcsin \left(\frac{n_{\mathrm{ext}}\mathrm{\&rho;}}{n_{S_2}{r}_3}\right)$

N wherein _Ext, n _S1, n _S2It is the optical index separately of environment, first spheroid (layer 12 among Fig. 1) and second spheroid (layer 10 among Fig. 1) of object outside; r ₁, r ₂, r ₃Be the radius separately at three interfaces limiting by two-layer object, r ₁Be the external radius of skin 12, r ₂Be the inside radius (therefore being the external radius of layer 10) of this layer 12, r ₃It is the inside radius of layer 10; And f represents the focal length of lens 4.

Caustic surface has following formula with intersecting of sensor plane:

$\frac{{\&PartialD;R}_u^{*}\left(\mathrm{\&rho;}\right)}{\&PartialD;\mathrm{\&rho;}}=0.$

For a fixed position of sensor, parameter ρ ^*Be separating of previous formula.Therefore, the radius R of desirable key light ring (distortion that does not promptly have inside surface 18) _cBe such: R _c=h ₁(ρ ^*).

Consider the acquisition of measurement result below.

By means of interference device at the optical axis place of object and near the utmost point of this object

The interferometry that two-layer object carries out is measured the measurement result that every layer thickness directly is provided.

The backlighting photography phase images comprises, as see the ring of light that obtains by traditional sub-pix profile testing method.The center of the outside surface by calculating two-layer object and the measurement result that the distance between the profile check point obtains the backlight photographic process.

Consider the analysis of back illumination backlight photographic process now.

The inwall of two-layer object can have surface deformation.These distortion can be by following simulation (modeliser sets up model):

-description object interference ε inwall, on the radius of this spheroid ₁,

-interference ε on normal in the plane of determining by the optical axis 16 (center O of object is on this axle) of the object lens 4 of the reflection spot of the light on the object inwall and Fig. 1 (P), at spheroid ₂, and

-perpendicular to interference ε in the plane (Q) of plane (P), on normal ₃

About disturbing ε ₁, ε ₂, ε ₃With their the expression formula η of rank i of first order derivative ⁱExpression.

Make ρ ∈ R and θ ∈ [0,2 π [and occur as light source from collimation, at polar coordinates perpendicular to the light the plane of optical axis,

Make R ∈ R and α ∈ [0,2 π [and as with the polar coordinates of the light in the specific plane of this sensor of the sensor cross of observing system.

Make R ^*(ρ) as the radius of the ring of light that in ideal situation, (that is to say any interference of the inside surface that does not have two-layer object).

Suppose to disturb ε ₁, ε ₂, ε ₃Be little C ¹Value, it means that they are at R ²On have C ¹Level, and these disturb and their first order derivative is very little.

Because the continuity of the rotational symmetry of optical system and interference, intersect (intersection, or run through) observing system sensor the plane light polar coordinates (R, α) can be write as following formula:

$\left\{\begin{array}{c}R(\mathrm{\&rho;},\mathrm{\&theta;})=R^{*}\left(\mathrm{\&rho;}\right)+a_1\left(\mathrm{\&rho;}\right){\mathrm{\&epsiv;}}_1(\mathrm{\&rho;},\mathrm{\&theta;})+a_2\left(\mathrm{\&rho;}\right){\mathrm{\&epsiv;}}_2(\mathrm{\&rho;},\mathrm{\&theta;})+{\mathrm{\&eta;}}^2\\ \mathrm{\&alpha;}(\mathrm{\&rho;},\mathrm{\&theta;})=\mathrm{\&theta;}+a_3\left(\mathrm{\&rho;}\right){\mathrm{\&epsiv;}}_3(\mathrm{\&rho;},\mathrm{\&theta;})+{\mathrm{\&eta;}}^2\end{array}\right.$

A1 wherein, a2, a3 be only depend on optical system attribute real function and be smooth (smoothly), that is to say on R it is indeterminate difference.

The equation of caustic surface usually calculates from following equation:

$\frac{\&PartialD;R\left(\mathrm{\&rho;}\right)}{\&PartialD;\mathrm{\&rho;}}=0.$

Therefore can be written as:

θ(ρ，α)＝α-a ₃(ρ)ε ₃(ρ，α)+η ²

The equation qualification of any light that therefore, occur from optical system and that intersects with viewing plane (plane of sensor) is as follows:

-coordinate system (ρ, α) equation of the R in is:

R(ρ ^*，θ)＝R ^*(ρ ^*)+a ₁(ρ ^*)ε ₁(ρ ^*，θ)+a ₂(ρ ^*)ε ₂(ρ ^*，θ)+η ²

-and in this coordinate system, the equation of caustic surface usually by $\frac{\&PartialD;R\left(\mathrm{\&rho;}\right)}{\&PartialD;\mathrm{\&rho;}}=0$ Provide.

Be noted that and disturb ε ₃Not influence of ring of light radius to single order level (premier ordre).Therefore coordinate system (ρ, α) in the equation of the ring of light (disturbed caustic surface) of distortion write as single order:

R _c(α)＝R ^*(ρ ^*)+a ₁(ρ ^*)ε ₁(ρ ^*，α)+a ₂(ρ ^*)ε ₂(ρ ^*，α)+η ²

Above equation is very important, because realized use to the measurement result on the back illumination backlighting photography phase images from this equation.The feasible deformation epsilon that can collect about desirable spheroid of this equation ₁(ρ ^*, α) and ε ₂(ρ ^*, all information α).

Also exist and following disturbing ε ₁(ρ, θ) and ε ₃(ρ, θ) relation between:

Wherein

Be in the reflection spot of the inside surface 18 of layer 10 and the angle between the optical axis in plane (P).

Therefore can rebuild the θ (ρ of single order according to angle [alpha] ^*, α), angle [alpha] is the angle of observing.Yet, for following application, do not consider this correction, because it has no significant effect net result.

Consider the space estimation of the inside surface of two-layer object now.

Provided the information of surface state of the inwall of relevant two-layer object by back illumination backlight photographic process and data that interferometry provides.Therefore be necessary to make measurement result consistent so that estimation influences the distortion of the inside surface of this object.

For further part, must consider as preceding angle θ and it and another angle according to the inventive method Combine, so that form the coordinate system of Eulerian coordinates type, its initial point is the center O of object.

The distortion of spheroid is usually by spheric harmonic function

Simulation, wherein i ∈ N.In this respect can be with reference to following document:

H?Groemer，Geometric?Applications?of?Fourier?Series?andSpherical?Harmonics，Cambridge?University?Press，1996.

Therefore consider pattern (or distortion) naturally with inside surface

Linear combination as spheric harmonic function:

Wherein n is nature (limited) integer.

Therefore, obtain the linear relationship between the interference of measurement result and inside surface state, these linear relationships have unknown amplitude λ _i, i=1 wherein ..., n.

Be noted that in above-mentioned, disturb ε ₁, ε ₂, ε ₃Be independently.Yet, in the example that the present invention considers, distortion

Corresponding to interference

And two are disturbed ε in addition ₂And ε ₃Disturb ε with first ₁Interrelate.This just as much as to say ε is disturbed in decision fully ₁, ε ₂, ε ₃

As explained before, back illumination backlight photographic process will connect in direct measurement on the image and the distortion that appears on the object inwall.In addition, considered that the light (it is the deformation reason that causes the ring of light) from collimated light source does not occur from initial contact plane.Being deformed in of considering be for:

This equation is derived the system of a plurality of linear equations, and its variable is λ _iValue, i=1 wherein ..., n.The quantity of equation is the quantity of angle [alpha] of being considered in this system, and the radius value of the ring of light detects from foregoing profile.

Use least square method, estimate the mean value of inner wall thickness of two-layer object and the distortion of variable quantity.

Interferometry directly interrelates the linear combination of amounts of thickness variation in the observed zone and spheric harmonic function, because the measurement result of interferometry is a kind of simple reading of inner wall deformation.

Therefore, by reconfiguring the measurement result that obtains by interferometry and back illumination backlight photographic process,, obtained total estimation to the inner wall surface state of two-layer object by means of algorithm based on least square method.

Fig. 3 and Fig. 4 show the example of the space representation of the two-layer object inwall that carries out according to the present invention.Fig. 3 is the image on the surface of representation, and Fig. 4 shows this surperficial xsect I and II.These illustrate the distortion of reinforcement, because they are sightless for naked eyes.The estimated value that goes out to obtain is added (stack) on real surface on inspection.

Therefore as can be seen, in the present invention, the analysis of being undertaken by back illumination backlight photographic process makes and the distortion (in the distortion on the bidimensional) of the ring of light can be interrelated with the distortion (3 D deformation) that appears on the inside surface with two-layer translucent or clear hollow object.Should also be noted that known method can not change the two dimension distortion into 3 D deformation by means of single-view.

Measuring method and the feasible roughness that can estimate the inside surface of translucent or transparent two-layer hollow object of combining of interferometric method by back illumination backlight photographic process.By means of these two kinds of methods (it is applied in and does not exist together), dimension information (dimensionalinformation) is merged.

In the present invention, can replace interferometry to measure with measuring along the second backlight photographic process of not parallel observation axle with the observation axle that carries out the measurement of the first backlight photographic process.In addition, if along second observe observation that axle carries out be not complete (fully) but undertaken by slit, then the explanation to the measurement of backlight photographic process will be consistent.

Also can measure the replacement interferometry with the second back illumination backlight photographic process of carrying out along the observation axle that is used for the measurement of the first back illumination backlight photographic process and measure, prerequisite is to make object carry out this second measurement after itself rotates.

Therefore, this object also allows to use previous described method around the rotation of itself and the use of single backlight photograph observation axle, be that the analysis of caustic surface image makes and can date back to three-dimensional information and the unanimity of data (r é conciliation thus, or conciliate) so that rebuild the complete three-dimensional estimation of inside surface state.

Be used to implement as the backlight photographic means of the method for the object of the invention and interferometric measuring means in following description.

The backlight photographic means schematically is shown among Fig. 5, and comprise visible light source 19, be used to calibrate the adjustable apparatus 20 and the image acquiring device of this light source, this image acquiring device comprises the lens 22 of the device 24 that provides the numerical aperture (or having suitable numerical aperture) that is used to change lens.

After the lens is ccd sensor 26 (electric charge (charge) transfer device), and it provides image processing apparatus 28, and display device 30 is connected with image processing apparatus 28.

The double-deck hollow sphere 32 of hope research is placed on and makes the center of spheroid be arranged on basically on the optical axis 34 of lens 22 between light source 19 and the lens 22.This axle 34 constitutes observes axle, obtains the image of object along this observation axle.The lens 22 feasible images of cutting plane on ccd sensor 26 that can form hollow sphere 32.

Fig. 6 is the synoptic diagram of interferometric measuring means.More specifically, it is the interference spectrum device that is used for measuring thickness under the situation that does not have contact.

This device comprises white light source 35, one composition shape lens 36, telescope 38, and signal light transmission is learned fiber 40, spectrometer 42 and computing machine 44.

Light source 35 is used to illuminate object to be characterized 46.The illuminating bundle that is provided by this light source is transmitted by optical fiber 48 and is shaped by one group of lens 36, so that make the profile of this light beam be suitable for the geometric configuration of the object of studying.

Telescope 38 for example is to be numbered the QM100 type by what Questar company sold, is used to illuminate object to be analyzed and collects reflected light.The QM100 telescope allows the operating distance D from 15cm to 38cm scope.

In telescopical outlet, the light signal of reflection is launched into optical fiber 40 and sends until spectrometer 42 so that obtain channeled spectrum (or claiming channel spectrum).Provide injector 50 to be used for the light beam from fiber 40 is mapped to spectrometer.

Channeled spectrum is transmitted until computing machine 44 so that analyzed.This computing machine provides the device 52 that is used to show the result that obtains.

Let us is got back to main aspect of the present invention.The present invention relates generally to a kind of method of distortion of the inside surface that is used for determining two-layer object, and the essential element of this method (key element) is:

-be called as the analysis of the physical phenomenon of " caustic surface ", include the information of the distortion of closing inside surface, this caustic surface is defined by the inward flange of the ring of light that subject image had that obtains by back illumination backlight photographic process.

-determine by back illumination backlighting photography phase system (chain, the chain) information of Guan Chaing, the two dimension of the ring of light disturb and provide the three-dimensional information that relevant object inside surface is out of shape, and

-establish to merge the principle (use least square method and suitably set up the model of object inner wall deformation) of incomplete physical measurements.

Other application of the present invention are below described.

The method according to this invention is the previously described type that is used to characterize the distortion of two-layer hollow sphere, can be applied to characterize the distortion of two-layer hollow circular cylinder.

Can use identical light source shown in the meaning property and identical Image Acquisition chain (system) as shown in Figure 7, wherein right cylinder is labeled as 54.So two white ribbons about two-layer cylindrical inside surface appear on the backlighting photography phase images.Therefore must rethink the simulation (or modelling) of interference.

Identical method also can be used to characterize the ellipsoidal distortion of two-layer hollow.

Also can use identical light source shown in the meaning property and identical Image Acquisition chain as shown in Figure 8, wherein ellipsoid has mark 56.So on the backlighting photography phase images, occur one with the relevant white ribbon of two-layer ellipsoidal inside surface.Therefore also must rethink the simulation (or modelling) of interference.

Identical method also can be used to characterize two-layer hollow oblate spheroid (

Or the title ellipsoid, spheroid, globoid) distortion.

Also can use identical light source and identical Image Acquisition chain.So a white ribbon relevant on the backlighting photography phase images, occurs with the inside surface of two-layer oblate spheroid.Therefore also must rethink the simulation (or modelling) of interference.

The present invention also is applied to characterize the refractive index of two-layer object: the equation of the definition ring of light radius that provides more than the use, can determine the light refractive index of each layer in two-layer, and will determine the size of each layer in two-layer in advance by means of another measuring system.

Use also can be determined the optical index of each layer by another ring of light of the image of back illumination backlight photographic process acquisition.

Therefore, from single backlight photograph photo, the optical index of desirable two-layer object (that is to say and do not have little distortion) is characterized.

Claims (10)

1. one kind is used for the three-dimensional hollow (8,32,46 that contactless measurement has inwall (18), 54,56) method, described object comprise skin (12) and internal layer (10), described object is translucent or transparent to visible light, and described method is characterised in that

By the single-view backlit shadowgraphy method, along the first observation axle (34),, obtain the image of described object by observe described object with visible light, described image comprises at least one isolychn,

The equation that foundation connects at least one geometric parameter of at least one optics geometric parameter of described object and described isolychn,

Determine the described geometric parameter of described isolychn, and

Determine described optics geometric parameter by means of described equation and definite thus geometric parameter,

Wherein,

From the image and the described equation of above-mentioned object, carry out the three-dimensional representation of inwall (18) on the zone in the equator of close described object of described object, described representation provides first group of data,

Determine the thickness of the described internal layer (10) of described object,

Determine the second group data relevant from the thickness of determining thus with the distortion of described internal layer, and

Carry out the representation of the whole inwall (18) of described object by means of described first group of data and second group of data.

2. method according to claim 1 wherein, is based upon the distortion of described isolychn and appears at linear relationship between the interference on the described inwall (18) of described object, so that determine described second group of data.

3. according to each described method in claim 1 and 2, wherein, the thickness of the internal layer of described object (18) is determined by interfere measurement technique.

4. according to each described method in claim 1 and 2, wherein, determine the thickness of the internal layer (18) of described object by backlight photographic process measurement of carrying out along the second parallel observation axle with the described first observation axle (34).

5. according to each described method in claim 1 and 2, wherein, after the rotation of carrying out described object, determine the thickness of the internal layer (18) of described object by the backlight photographic process measurement of carrying out along the described first observation axle (34).

6. according to each described method in claim 1 and 2, wherein, by means of least square method by described first group of data and described second group of data combination are carried out the representation of the whole inwall (18) of described object.

7. method according to claim 3, wherein, by means of least square method by described first group of data and described second group of data combination are carried out the representation of the whole inwall (18) of described object.

8. method according to claim 4, wherein, by means of least square method by described first group of data and described second group of data combination are carried out the representation of the whole inwall (18) of described object.

9. method according to claim 5, wherein, by means of least square method by described first group of data and described second group of data combination are carried out the representation of the whole inwall (18) of described object.

10. one kind is used for the three-dimensional hollow (8,32,46 that contactless measurement has inwall (18), 54,56) method, described object comprise skin (12) and internal layer (10), described object is translucent or transparent to visible light, and described method is characterised in that

By the single-view backlit shadowgraphy method, along the first observation axle (34),, obtain the image of described object by observe described object with visible light, described image comprises at least one isolychn,

The equation that foundation connects at least one geometric parameter of at least one optics geometric parameter of above-mentioned object and described isolychn,

Determine the described geometric parameter of described isolychn, and

Determine described optics geometric parameter by means of described equation and definite thus geometric parameter,

Wherein, determine respectively two optics geometric parameters that the refractive index by the refractive index of described internal layer (10) and described skin (12) constitutes from two geometric parameters that constitute by the thickness and the described outer field thickness of described internal layer respectively.

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